Power transmission

ABSTRACT

A hydraulic motor of the rotary sliding vane type has two pairs of displacement chambers of different size, either one or both of which may be utilized for driving the motor by selective control of the inlet and outlet porting. The cam ring against which the vanes are projected has four dwells of the same major diameter which are connected by eight ramps with four dwells of minor diameter, one pair of the latter being more than 25 percent greater in diameter than the other. This avoids functional difficulties inherent in similar vane motors in which all of the four minor dwells are of the same diameter and the two pairs of major dwells are of different diameter.

United States Patent 1 Gowie Mar. 28 1972 [54] POWER TRANSMISSION 3,266,429 8/l966 Stockett ..418/15 [72] Inventor: John D. Gowie, Warren, Mich. Primary Examiner Car]ton Rflcmyle [73] Assignee: Sperry Rand Corporation, Troy, Mich. A an xamin hn J Vrablik Attorney-Van Meter and George [22] Filed: Oct. 29, 1970 [2]] Appl. No.: 85,061 ABSTRACT A hydraulic motor of the rotary sliding vane type has two pairs 52 us. (:1 ..418/15, 413/150, 418/259 displacement chambers different size, either We [51] lntclmu mfolc F03: F046 1/00 of which may be utilized for driving the motor by selective [58] Field of Search 418/8 13 15 31 150 259 and Pming' The against which the vanes are projected has four dwells of the same major diameter which are connected by eight ramps with four dwells of minor diameter one air of the latter bein more 1 i1 1 P g [56] Re C ed than 25 percent greater in diameter than the other. This UNITED STATES PATENTS avoids functional difficulties inherent in similar vane motors in which all of the four minor dwells are of the same diameter 4401120 1 1/1 390 F Sythe "418/8 and the two pairs of major dwells are of different diameter. 2,280,272 4/1942 Sullivan "418/15 2,777,396 1 1957 Adams et al. ..4l8/266 1 Claims, 1 Drawing Figure PATENTEDHAR 28 I972 NVEN TOR. Z). Goalie A TTOR N EY POWER TRANSMISSION In hydraulic motors of the rotary sliding vane type, and particularly in those designed for slow speed and high torque operation, it has been proposed to provide two pairs of displacement chambers of unequal displacement and, through the means of suitable porting and valving, to selectively direct pressure fluid from a suitable source to either one or to both of the displacement chambers, thus having available three different effective displacements. In such motors, the vanes are projected against a cam ring having four major dwells and four minor dwells connected by eight ramps. To achieve the necessary displacement differences, one pair of major dwells is made of greater diameter than the other; however, practical considerations experienced in the functioning of such motors limits the effective difference in displacement to approximately 25 percent and difierences beyond this value lead to faulty operation, exhibited by chatter and jerky rotation.

it is an object of the present invention to provide an improved triple displacement hydraulic motor of the rotary sliding vane type in which these difficulties are overcome and the difference in displacement between one pair of chambers and the other may be greater than 25 percent.

This object is accomplished by the provision of a rotary vane motor having a slotted rotor carrying a plurality of radially slidable vanes and a stator including a ported housing and a cam ring against which the outer ends of the vanes are projected, the cam ring having four major dwells connected by eight ramps with four minor dwells, and the porting including a port at each ramp, and which has the improvement which provides minor dwells, one pair of which is more than 25 percent larger in diameter than the other pair. in the drawing:

The single figure represents a diagrammatic cross-sectional view of a vane motor incorporating a preferred form of the present invention.

A shaft is splined to a rotor 12 having a plurality of vane slots 14 which carry radially slidable vanes 16. Suitable means for projecting the vane 16 outwardly, as by the use of springs or by the application of fluid pressure at the bottom of the vane slots 14, may be provided in any well-known manner. The stator of the motor includes a cam ring 18 and the other body parts 20 which include the terminal connections and the necessary porting to feed driving fluid to and from the displacement chambers of the motor as well as bearings for the shaft 10, cheek plates for the rotor 12, and the other usual components of such devices.

The cam ring 18, in accordance with the present invention, is formed to provide two pairs of displacement chambers 22 and 24 of different displacement. These areformed by the provision of four circular dwells 26, all of equal diameter, and which are termed the major dwells, and by the provision of two pairs of minor dwells 28 and 30, the dwells 28 being at least 25 percent larger in diameter than the dwells 30. The four major dwells and the four minor dwells are connected by a series of eight ramps, not numbered. Adjacent each ramp there is a lateral port, designated in pairs as 32, 34, 36 and 38.

In operation, with the motor connected to a suitable constant displacement source and with suitable valving arranged to change the connections to the various inlet and outlet ports, the motor may be operated at high speed and low torque, that is to say at minimum displacement, in a counterclockwise direction, by admitting fluid only to the ports 36 and exhausting it only from the ports 38 while the ports 32 and 34 are interconnected. To operate the motor at anintermediate lower speed and higher torque, the connections are changed so that fluid is admitted through ports 32 and exhausted through ports 34 with ports 36 and 38 interconnected. For operation at max- 7 imum displacement, that is to say full torque and lowest speed, fluid is admitted to both the ports 32 and the ports 36 and exhausted from the ports 34 and 38, thus adding the displacements of chambers 22 to that of chambers 24. For clockwise rotation,.a similar but opposite arrangement of connections will be established.

By making the difference in displacement between one pair of chambers 22 and the other pair 24, the result of a difference between the minor diameters 28 and 30 the operational difficulties which are experienced with other triple displacement vane motors are avoided and problems otherwise encountered in achieving regular rotation and smooth travel of the vanes inwardly and outwardly are avoided.

I claim 1. In a rotary vane motor having a slotted rotor carrying a plurality of radially slidable vanes and a stator including a ported housing and a cam ring against which the outer ends of the vanes are projected, the cam ring having four major dwells connected by eight ramps with four minor dwells, and the porting including a port at each ramp, that improvement in which the minor dwells include one pair which is more than 25 percent larger in diameter that the other pair. 

1. In a rotary vane motor having a slotted rotor carrying a plurality of radially slidable vanes and a stator including a ported housing and a cam ring against which the outer ends of the vanes are projected, the cam ring having four major dwells connected by eight ramps with four minor dwells, and the porting including a port at each ramp, that improvement in which the minor dwells include one pair which is more than 25 percent larger in diameter than the other pair. 